1. Field of the Invention
This invention relates to a camera, and more particularly, to a camera capable of performing a multiphotometric operation.
2. Description of the Prior Art
There have been known cameras of the kind arranged to repeatedly perform a light measuring operation a plurality of times; to obtain a control exposure value (to be used for controlling an actual shutter-speed or -time or an actual aperture value) by computing a measured light value on every performance of the repeating light measuring operation; and to display the measured light value thus obtained each time the light measuring operation is performed along with the control exposure value. An example of cameras of this kind is disclosed in Japanese Laid-Open Patent Application No. Sho 59-2024.
The display devices of the cameras of the above-stated kind have been arranged to display the exposure value and the measured light value of each light measuring performance in absolute values. This arrangement has necessitated use of a display device which is capable of making a display on a display scale over a wide range. The prior art arrangement thus has resulted in a large display device. For example, the device disclosed in the above-cited Japanese patent application is arranged as follows: In the case of a multi-photometric operation under an automatic exposure control condition, a shutter time value is obtained by performing a computing operation on a film sensitivity information value and the aperture value of the photo-taking lens of the camera, together with each of the measured light values obtained by a plurality of light measuring performances; the shutter time value thus obtained is displayed in a dot display on a scale provided for shutter time values; and then, a control shutter time value, which is obtained by computing the film sensitivity information value and the aperture value of the lens together with a control light measurement value obtained in a predetermined algorithm from the measured light values obtained by the plurality of light measuring performances, is displayed in a bar display on the above-stated scale. The camera is thus arranged to make a so-called absolute value display and is incapable of making a relative value display in the event of multi-photometric operation under an automatic exposure control condition.
In a conceivable method for solving this problem, a display device is arranged to make a relative value display showing the difference or a deviation value of the measured light value of each of the plurality of light measuring performances from the above-stated control exposure value with the latter arranged in the middle of the display. However, the control exposure value might be changed and renewed, accordingly as the multi-photometic operation is performed. In that event, the deviation value of the measured light value of each light measuring performance from the control exposure value is also renewed accordingly. Then, with the light measurement repeated, a plurality of times, it becomes difficult to accurately correlate a specific displayed deviation value with one of the plurality of performances of the light measuring operation.
Further, the camera capable of performing the multi-photometric operation enables the photographer to perform a photographing operation with a sufficiently high grade of photographic technique as it gives an exposure value suited for attaining a desired photographic effect. Whereas, in the conventional camera, exposure correction is arranged to be made by setting a corrected value through a correction setting dial or the like. Once a correction value is set, the set correction value cannot be cancelled unless the set state of the correction setting dial is manually operated to cancel the setting value. In other words, after a measured light value obtained by a multi-photometric operation has been corrected by setting a correction value, the set correction value remains as it is even if a further photometric operation is performed. Therefore, in that event, the previously set correction value prevents the photographer from knowing an actual measured value obtained by the further photometric operation.
The camera capable of performing the multi-photometric operation is provided with a light measuring button which is arranged for the multi-photometric operation separately from a shutter release button, because: In the case of a camera of the kind having one and the same button arranged to perform combined functions as a light measuring button and a shutter release button and to perform a photometric operation in response to the first stroke of a pushing operation on the release button, a multi-photometric operation can be accomplished by repeating the pushing operation just to the first stroke a desired number of times. However, after the multi-photometric operation, when the release button is pushed down to the second stroke thereof for shutter release, this pushing operation inevitably includes the first stroke as well as the second stroke. Then, this results in a new light measuring operation which changes a control exposure value obtained through the multi-photometric operation.
However, even in the camera of the kind having a light measuring button separate from the shutter release button, if the release button is pushed down while the light measuring button is being pushed down, a new unintended light measuring operation would be caused by the depressing operation on the release button. In that event, the light value which is measured by pushing the light measuring button would be changed by the unintended light measuring operation.